U.S. Pat. No. 5,252,261 discloses an adjustment safeguard for the set screw of a carburetor which consists of a cap held non-rotatably on the head of the set screw and is surrounded with minimum radial play by an approximately coaxially positioned wall sleeve fixed to the housing. The cap has associated therewith in the rotational direction of the set screw a stop in the wall sleeve which is fixed to the housing such that once the cap has been placed in position on the set screw, the user is only still able to adjust the set screw about a structurally fixed, limited angle of rotation. This ensures that once the carburetor has been preset during manufacture, the user is still only able to modify the preset settings within a limited range in which too rich a fuel setting and too poor a fuel setting are both prevented. Too rich a setting is negative for the exhaust while too poor a setting impairs the operating reliability of the internal combustion engine.
The cap of the adjustment safeguard is pressed onto the head of the set screw which has an outer knurling or toothing. A receiving space with an inner knurling or toothing is provided in a corresponding manner in the connecting portion of the cap such that it is only still possible to adjust the set screw together with the cap.
The adjustment safeguard itself is to be protected against manipulation by a user. The adjustment safeguard consequently has to be designed such that it is hardly possible for a user to destroy the limiting means of the adjustment range, even maliciously.